1. Field of the Invention
The present invention relates to a stator used in a rotational electric machine such as an electrical motor or a generator, and a manufacturing method therefor.
Priority is claimed on Japanese Patent Application No. 2005-191556, filed Jun. 30, 2005, the contents of which are incorporated herein by reference.
2. Description of the Related Art
There is conventionally known a three-phase motor that drives a rotor in three phases by means of a stator in which three stator windings of a U-phase, a V-phase, and a W-phase are concentrically wound on stator cores for each of the three phases.
In order to prevent the flow of excess current in such windings, the windings are covered with an insulation coating. In this case, there is known thermal fusing technology for having the end of a coil winding conduct electricity with a fusing terminal member.
There are windings of a stator so-called round wire with a circular cross section and so-called rectangular wire with a rectangular cross section. Japanese Patent Granted Publication No. 3346297 discloses thermal fusing of rectangular wire, while Japanese Unexamined Patent Application, First Publication No. 2003-79079 and Japanese Unexamined Patent Application, First Publication No. 2005-51999 disclose thermal fusing of round wire.
When a round wire 51 that includes a lead wire 55 covered by an insulation coating 54 is fixed to a terminal 52, first the round wire 51 is inserted into the terminal 52 as shown in FIG. 8, with the terminal 52 then crimped in the state of a pair of electrodes 53 brought into contact from the outer sides of the terminal 52. Thereby, as shown in FIG. 9, the round wire 51 inserted into the terminal 52 is flattened, and the insulation coating 54 on the surface of the round wire 51 is pushed outward of the contact portions with the terminal 52. Then, when the terminal 52 is fused by passing electrical current between the pair of electrodes 53, the portion of the insulation coating 54 in contact with the terminal 52 is melted by the generated heat from the current to flow outward of the contact portions.
Thereby, the exposed lead wire 55 is welded to the terminal 52, so that the electrical contact between the round wire 51 and the terminal 52 is ensured.
However, in the case of thermal fusing being performed on a rectangular wire, the following problems arise when using conventional technology. Namely, when the rectangular wire 56 is inserted into the terminal 52 and the terminal 52 is crimped as shown in FIG. 10, the insulation coating 54 of the pressed rectangular wire 56 becomes sandwiched between the inner surfaces of the terminal 52. As a result, even if thermal fusing is performed on the terminal 52 by passing a current between the pair of electrodes 53, the insulation coating 54 that is sandwiched in the terminal 52 does not fuse, and so ends up remaining behind as residual coating 57. When this residual coating 57 is generated, there is the risk it may cause an increase in contact resistance and a decrease in the conductive performance.